In the fabrication of semiconductor devices, a silicon wafer or any other semi-conducting substrate must be processed in a plurality of processes conducted in a variety of process machines. In order to produce quality semiconductor devices, a physical or chemical process conducted in a process machine must be closely monitored and controlled. This may be a difficult task since a commercially available process machine may not always provide such capabilities. For instance, as shown in FIG. 1, in a plasma chamber such as that supplied by Applied Materials, Inc. of Santa Clara, Calif. (T-5000 chemical vapor deposition system), the process chamber 10 is only provided with a narrow view port 12 in one of the sidewalls of the chamber. In this specific chamber, the view port has a dimension of 75.8 mm in width, 23.7 mm in depth and 6.32 mm in height. Such a narrow opening makes it very difficult for someone to mount a monitoring device other than observing by the naked eye.
In the process machine shown in FIG. 1, the generation of plasma for deposition must be carefully monitored and controlled in order to ensure the deposition of a high quality film. One of the important parameters to be monitored is the generation of plasma or the intensity of the plasma generated. In general, as intended by the machine manufacturer, the monitoring of plasma discharge is performed through the view port 12 by observation with the naked eye of an operator. Due to the small height of the view port 12, i.e., 6.32 mm, a regular optical detector cannot be mounted directly to the view port when more accurate monitoring than that possible by naked eye is desired. One possible method to accomplish this task is the use of optical fibers to guide out the emitted light during plasma excitation to an optical detector located nearby. Suitable optical detectors such as photo diode, photo multiplier tube, array detectors are commonly used to convert the emission intensity transported by an optical fiber into electronic signals for signal processing.
To further enhance the collective efficiency of the emission signals by using an optical fiber, a collective lens can be added at the front end of the fiber. The use of the additional lens further complicates the mounting of the optical fiber to the narrow view port of the process machine shown in FIG. 1. The mounting of the fiber and the lens to a narrow view port becomes a very difficult task. If they are not mounted properly, these optical components are susceptible to external interferences such as mechanical vibrations which may lead to a dislocation of the fiber/lens from the view port, or a change in the optical signal collective status and thus affecting the results of the optical monitoring of plasma discharge.
In addition, most semiconductor process equipment is a stand alone system which is no longer suitable for further mechanical modifications to be made on the equipment body. It is therefore an important task to design a compact, easy-to-mount and easy-to-dismount mounting device without the need to modify a process equipment such that optical monitoring of a process in a process chamber can be achieved.
It is therefore an object of the present invention to provide a mounting system for engaging a monitor to a process chamber that does not have the drawbacks or shortcomings of the conventional mounting devices.
It is another object of the present invention to provide a mounting device for engaging a monitor to a process chamber wherein the mounting device is engaged to the process chamber solely by frictional means.
It is a further object of the present invention to provide a frictional mount for engaging a monitor to a process chamber such that the operating conditions of the chamber can be monitored by optical fiber.
It is another further object of the present invention to provide a frictional mount for engaging a monitor to a process chamber that has a simple construction of a base member, a compressible member and a pressing member.
It is still another object of the present invention to provide a frictional mount for engaging a monitor to a process chamber by utilizing a compressible plate in a mount which expands in a lateral direction when compressed in a perpendicular direction for providing required frictional force.
It is yet another object of the present invention to provide a frictional mount for engaging a monitor to a process chamber by utilizing a polyurethane compressible plate sandwiched between a base plate and a pressing plate such that when the polyurethane plate is compressed, it expands in the lateral direction to engage the internal peripheral surface of a view port on a process machine.
It is still another further object of the present invention to provide a method for engaging a monitor to a process chamber by providing a compressible plate sandwiched in-between a base plate and a pressing plate such that the compressible plate expands in a lateral direction when compressed by the other two plates to provide the necessary frictional force.
It is yet another further object of the present invention to provide a method for mounting an optical fiber monitor to a plasma deposition chamber by utilizing a polyurethane compressible plate sandwiched between a base plate and a pressing plate such that when the polyurethane plate is compressed, it expands in a lateral direction to provide the necessary frictional force between the mount and a view port of the plasma chamber.